US3432260A - Process for the manufacture of sodium tripolyphosphate - Google Patents

Process for the manufacture of sodium tripolyphosphate Download PDF

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Publication number
US3432260A
US3432260A US694626A US3432260DA US3432260A US 3432260 A US3432260 A US 3432260A US 694626 A US694626 A US 694626A US 3432260D A US3432260D A US 3432260DA US 3432260 A US3432260 A US 3432260A
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salt
kiln
temperature
maddrells
heating
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Expired - Lifetime
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US694626A
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English (en)
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Winfried Kern
Gero Heymer
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Knapsack AG
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Knapsack AG
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/38—Condensed phosphates
    • C01B25/44—Metaphosphates
    • C01B25/445—Metaphosphates of alkali metals

Definitions

  • the present invention relates to a process for the manufacture of water-insoluble sodium polyphosphate, socalled Maddrells salt, by thermal treatment of monobasic sodium phosphate, inside a kiln.
  • Maddrells salt can be produced by dehydration of monobasic sodium phosphate. Depending on the reaction conditions used, the dehydration is found to entail more or less the formation of water-soluble phosphates, such as acid sodium pyrophosphate, sodium trimetaphosphate or long chain soluble polyphosphates.
  • Maddrells salt in a form fairly free from water-soluble phosphates, especially when the compound is intended for use as a polishing agent for tooth pastes. More particularly, it is desirable to obtain products containing less than 1% by weight soluble phosphates, which are known to have strong complex-forming properties and, therefore, a deleterious effect upon tooth enamel.
  • the monobasic sodium phosphate is preferably heated by conveying it at a constant rate through a kiln arranged to establish a suitable temperature curve therein.
  • FIGURE 1 The test results obtained are indicated in the accompanying drawing, FIGURE 1.
  • Small amounts of 0.5 gram NaH PO placed in a special apparatus were heated to a temperature of 450 C. at quite specific heating rates.
  • the tests were carried out in stationary air. Heating rates between 5 and 10 degrees per minute have been found to produce Maddrells salt in optimum yields, which decrease when the heating rates are outside the above range. Heating rates of more than 10 degrees per minute have furthermore been found to produce strongly sintered final product, while heating rates of 10 degrees per minute or less always produce readily friable material.
  • the substance was post-annealed for 30 minutes at 450 C. for complete dehydration.
  • the resulting final products were then found to be comprised of mixtures of Maddrells salt with sodium trimetaphosphate.
  • a kiln 2 meters long was provided with filament windings (not shown in the drawing) so as to establish therein a temperature curve such as shown in the drawing, and small boats filled with NaH PO were slowly passed through the kiln so as to increase the temperature at a rate of 5 to 10 degrees per minute.
  • Resulting steam (1) was exhausted from the reaction tube. Failing this, the material will be found strongly to sinter together and predominantly to form sodium trimetaphosphate.
  • steam was exhausted there was obtained a final product which was comprised of practically pure Maddrells salt and contained no more than 0.5 to 1% by Weight soluble phosphates.
  • Example 1 50 grams NaH PO placed in a small stainless sheet metal boat were conveyed through the kiln, at a constant rate of 4.6 cm./minute. The kiln had an overall length of 2 meters. The boat was thus allowed to remain therein for a period of 43 minute. The temperature increase produced on passing the boat through the kiln was equal to 10.6 degrees per minute.
  • Example 2 shows how matters change on heating the NaH PO feed material at varying heating rates.
  • the boat was maintained at that temperature for a further 33 minutes. In other words, the boat was allowed to remain in the kiln for a total period of 43 minutes, as in Example 1.
  • the final product (42 grams) was formed of only 12% Maddrells salt and of 88% soluble matter. It was furthermore found to be very hard and very difiicult to comminute.
  • the final product (42 grams) was formed of 64% Maddrells salt and of 36% water-soluble phosphates.
  • Example 4 500 grams NaH PO were placed in ten small stainless sheet metal boats and conveyed one after the other through the kiln, at a rate of 4.6 cm./min., corresponding to a temperature increase of 10.6 degrees per minute. 600 liters air per hour were simultaneously passed through the apparatus for removal of steam. The resulting final product (425 grams) was formed of 99.4% by weight Maddrells salt and obtained in the form of a very readily friable cake, which could be removed from the boats without difficulty. The proportion of soluble matter was found to be 0.6% by weight.
  • Example 5 650 grams NaH PO were placed in thirteen small boats, which were conveyed through the kiln at a rate of 2.8 cm./min., corresponding to a temperature increase of 6.5 degrees per minute. 300 liters air per hours were used for removal of steam. The final product (550 grams) was formed of 99.2% by weight Maddrells salt and 0.8% by weight soluble phosphates.
  • a process for manufacturing a Maddrell salt having less than 1% soluble phosphates in a continuous manner from monobasic sodium phosphate which comprises initially heating monobasic sodium phosphate reactant to about C. and thereafter raising the temperature at a constant rate of about 220 C. per minute to a final temperature of about 450 C.; maintaining the reactant material at that temperature for a period equal to about /3 of the time needed to raise the reactant from 150 C. to 450 C.; continuously removing steam therefrom during said heating.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
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  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Fertilizers (AREA)
US694626A 1967-01-02 1967-12-29 Process for the manufacture of sodium tripolyphosphate Expired - Lifetime US3432260A (en)

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DEK0061071 1967-01-02

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US3432260A true US3432260A (en) 1969-03-11

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US694626A Expired - Lifetime US3432260A (en) 1967-01-02 1967-12-29 Process for the manufacture of sodium tripolyphosphate

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US (1) US3432260A (pt)
AT (1) AT285527B (pt)
BE (1) BE708805A (pt)
CH (1) CH499459A (pt)
DE (1) DE1667561B1 (pt)
DK (1) DK120844B (pt)
FR (1) FR1549914A (pt)
GB (1) GB1200241A (pt)
NL (1) NL157277B (pt)
SE (1) SE318262B (pt)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115159488A (zh) * 2022-07-22 2022-10-11 承德莹科精细化工股份有限公司 一种高水溶性玻璃态偏磷酸钠的制备方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3543394A1 (de) * 1985-12-07 1987-06-11 Benckiser Knapsack Gmbh Verfahren zur herstellung von maddrellschem salz, sowie natriumdihydrogenphosphat, enthaltend 0,05 - 2,5 mol% phosphorsaeure oder ammoniumphosphat in statistischer verteilung

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2356799A (en) * 1943-05-27 1944-08-29 Monsanto Chemicals Process for producing insoluble sodium metaphosphate

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE753616C (de) * 1943-06-09 1952-03-27 Albert Ag Chem Werke Herstellung von polymeren, wasserunloeslichen Alkalimetaphosphaten

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2356799A (en) * 1943-05-27 1944-08-29 Monsanto Chemicals Process for producing insoluble sodium metaphosphate

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115159488A (zh) * 2022-07-22 2022-10-11 承德莹科精细化工股份有限公司 一种高水溶性玻璃态偏磷酸钠的制备方法
CN115159488B (zh) * 2022-07-22 2023-06-30 承德莹科精细化工股份有限公司 一种高水溶性玻璃态偏磷酸钠的制备方法

Also Published As

Publication number Publication date
CH499459A (de) 1970-11-30
SE318262B (pt) 1969-12-08
DK120844B (da) 1971-07-26
AT285527B (de) 1970-10-27
NL157277B (nl) 1978-07-17
FR1549914A (pt) 1968-12-13
NL6717848A (pt) 1968-07-03
BE708805A (pt) 1968-07-01
GB1200241A (en) 1970-07-29
DE1667561B1 (de) 1970-08-06

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